Agile thin film varactors that incorporate complex oxide materials with a paraelectric phase are known. The most commonly used materials include barium strontium titanate, strontium titanate, and the like. It is also known that dopants such as magnesium and lanthanum have been used to enhance desired performance properties such as tunability or to reduce undesired performance properties such as microwave power loss. In addition, temperature stability characteristics have been improved by grading thin film dopant concentrations or growing dopant-stratified heterostructures. However, the nano-structuring of such devices has been limited to the thickness of the thin films. As such, varactors provide increased tunability, reduced power losses, etc., would be desirable.